<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#div1 {width:100px; height:150px; background:red; position:absolute; right:0; bottom:0;}
</style>
<script>
window.onscroll=function()
{
	var oDiv=document.getElementById('div1');
	var scrollTop=document.documentElement.scrollTop||document.body.scrollTop;
	
	//oDiv.style.top=document.documentElement.clientHeight-oDiv.offsetHeight+scrollTop+'px';
	
	startMove(document.documentElement.clientHeight-oDiv.offsetHeight+scrollTop);
};
var timer=null;
function startMove(iTarget)
{
	var oDiv=document.getElementById('div1');
	
	clearInterval(timer);
	timer=setInterval(function(){
		var speed=(iTarget-oDiv.offsetTop)/4;
		speed=speed>0?Math.ceil(speed):Math.floor(speed);
		
		if(oDiv.offsetTop==iTarget)
		{
			clearInterval(timer);
		}
		else
		{
			oDiv.style.top=oDiv.offsetTop+speed+'px';
		}
		},30);
}
</script>
</head>

<body style="height:2000px;">
<div id="div1">
</div>
</body>
</html>
